PC help - how to get rid of e-regfix messages

[BadHair]

I keep getting Messanger messages telling me that critical errors have been detected and that I must immediately go to regfix.com to download a patch to repair. And other stuff in a similar vein that I'm pretty sure is a load of rubbish, especially as the regfix website is a sales site.
I've run Norton Antivirus and Lavasoft AdAware and come up with nothing.
Does anyone know how I can get rid of these bl**dy messages, as they're popping up every 60 seconds or so and driving me potty? All advice much appreciated.

I kept getting these messages constantly. I ignored them and I stopped receiving them (eventually)

can you block the sender from your msn?

It's not MSN as I don't have it. The box says Messenger Service and looks like it comes from Microsoft, but I'm pretty sure it doesn't as the site it directs you to is nothing to do with MS.

Have just had another one. It says:

Message from SYSTEM to ALERT on 7/18/2005 10:15:00 PM.
SECURITY ALERT:
Windows has detected registry errors on your computer!
Registry errors can cause potential data loss.
Microsoft recommends an immediate system scan.

Visit: www.winregedit.com for FREE registry scan.

I get lots of similar messages, all seeming to come from my computer. I stupidly visited the site once (winregedit is just one of many) and a scan showed there were 30-odd serious errors in my PC's registry. It then took me to another site where I was invited to buy a patch for $20.

I might be wrong on this but 30 or so serious errors would show some loss of performance, but everything is fine apart from the repeated messages.

Basically I think something has embedded itself somewhere and I need to get it out. But where to look? Done add/install programs but it was to clever for that and has hidden itself rather well.

Sorry to go on but its driving me nuts.

sorry bad hair didn't see this yesterday. It's a kind of hack (not a dangerous one, but annoying).

Go to control panel>services, find microsoft messenger service and disable it.